This invention relates to a thermal transfer recording medium, more particularly to a thermal transfer recording medium which can be prevented from film peel-off of the heat-fusible colorant layer and can be suitably used for printing for multiple times.
In the prior art, as the adhesion layer to be interposed between the support and the heat-fusible colorant layer, it has been disclosed to use polyester resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, vinyl chloride resin (see Japanese Unexamined Patent Publication No. 105579/1980), polyamide resin (see Japanese Unexamined Patent Publication No. 116193/1981), polyvinyl butyral resin, epoxy resin (see Japanese Unexamined Patent Publication No. 36698/1982) and saturated linear polyester resin (see Japanese Unexamined Patent Publication No. 96992/1984).
Since the heat-fusible colorant layer of the prior art employs a compound with relatively smaller polarity such as wax, higher fatty acid, etc. as a main component, when a polymer film with relatively greater polarity such as a polyester resin or a polyamide resin is used for the support, if an adhesive material with relatively greater polarity such as a polyvinyl butyral resin, an epoxy resin or a polyester resin is used in the adhesion layer, adhesive force with the support may be strengthened but the adhesive force with the colorant layer is weak, whereby film peel-off will readily occur at the interface between the colorant layer and the adhesion layer to make it difficult to obtain printing for multiple times. Particularly, this tendency becomes marked when the applied power is increased or an additive such as a surfactant, etc. is incorporated in the colorant layer. This film peel-off is liable to occur at the edge portion of the printed pattern, with the result that the so called white drop-out portion will be formed in the second printed pattern to give a very unclear letter.